Lipolysis is higher in patients with acquired immunodeficiency syndrome (AIDS) than in healthy control subjects. To evaluate whether this increase in lipolysis is related to increased (-adrenergic sensitivity, we compared the lipolytic response to epinephrine of six AIDS patients with that of six matched control subjects. Lipolysis was measured by infusion of [2H2]glycerol and [2H2]palmitate. The baseline rates of appearance of palmitate and glycerol were higher in AIDS patients. The absolute increase in lipolysis, an indicator of the responsiveness to epinephrine, was not different between groups for the rate of appearance of palmitate or glycerol. Plasma concentrations of epinephrine were not different between groups. Lipolysis was higher whereas the lipolytic response to epinephrine was normal in AIDS patients. Increased lipolytic sensitivity to catecholamines is not the cause of increased lipolysis in AIDS.